The present invention is an improvement of my co-pending application, Ser. No. 293,273 filed Aug. 17, 1981, which is a continuation-in-part of my application, Ser. No. 044,071 filed May 31, 1979 and now abandoned.
A transfer organ is an electronic organ which exactly duplicates the known properties of pipe organ sound, without employing permanent individual generating circuits for each separate tone. The instrument achieves complete individuality of each tone through keyboard-key-initiated, selective transfer of individualized tone-forming information from large memories for a note's voice to identical tone generating circuitry for as many keys as are activated at a given time. When a key is depressed, the organ circuit locates an available tone generating section, transfers the tone generating information to the section's circuits, and temporarily couples the key to the tone section by storing the key's code number so that the tone section can respond to further manipulation of that key. When the key is finally released and all of its keyed tones have completely decayed, the tone section is uncoupled from the key and cleared for possible coupling to another depressed key.
The stored, temporarily transferred, tone forming information can readily represent individualized tonal parameters essential to duplication of major properties of pipe organ sound. Such individualized parameters include among others:
(1) waveform throughout tonal attack, sustain, and decay; PA1 (2) amplitude throughout tonal attack, sustain, and decay; PA1 (3) tone frequency; PA1 (4) overall keying phase durations, or lengths of attack and decay; and PA1 (5) bidimensional, stereophonic decoupling of the sound of each note from that of every other note.
Dynamic keying circuitry permits duplication of the effects of tracker keying in a pipe organ.
Musical intervals which generate no beats are sometimes characterized as "perfect", or "pure". Early Western peoples had little liking for musical dissonance, and employed in their music, diatonic "just-temperament" scales having a small number of simple, interdependent numerical relations between their tone frequencies, no dissonances within the few commonly used musical intervals, excessive dissonances in uncommonly used intervals, few or no playable chords, and playability in only a single key. As cultural tolerance for dissonances increased, slight mistuning of several musical scale notes produced chromatic "mean-tone temperament" scales having perfect thirds, near-perfect fifths, reduced dissonances in other intervals, playable chords, playability in any musical key through employment of several extra keyboard keys, and useful musical contrasts between more and less dissonant intervals. Much excellent instrumental music was written for mean-tone temperature. By about 1700, however, chromatic "equal temperament" scales became the universal tuning pattern for most instruments, including pipe organs. Equal temperament scales have constant frequency ratios between all their adjacent notes, no perfect intervals except the octave, tolerable dissonances in most intervals, more playable chords, and playability in any musical keys without the help of extra keyboard keys. A small number of mean-tone concert pipe organs are being built today, contributing to a revival of the music written for them. It would be highly desirable, but difficult and prohibitively expensive, to construct a two-temperament pipe organ capable of playing both 15th and 17th Century music in the respective temperaments for which they were written.
While the large memories in my said co-pending application are programmable for any desired temperament, the said co-pending application disclosed no sufficient means enabling a single transfer organ to select and play in more than one temperament. No multi-temperament electronic organ can be found in the prior art. The prior art discloses electronic organs comprising various means for selecting different nominal organ voices other than those activated by initial arrays of stops, but no means for selecting different organ voices duplicating the known properties of pipe organ sound, or for selecting different musical temperaments.
My said co-pending application involves the keyboard-key-initiated transfer of tone forming information from large memories to small memories in pluralities of tone generating units. However, each tone generating unit contains a keying-phase control circuit which must be differently plugged or switched to generate (1) main tone attack or decay, (2) initial transients during tonal attack, or (3) terminal transients during tonal decay, through controlled setting and resetting series of cascaded flip flops. Each tone generating unit also contains an envelope-generating system comprising a first counter which presets a second counter which in turn causes a shift register to shift applied waveform data. The shifts of the waveform data generate normal power functions. A register-adder circuit inverts a generated power function during one half of an attack or decay interval, so that resulting sequences of normal and inverted power functions constitute sigmoid functions. Presetting of the first counter by a third counter varies the output pulse rate of the first counter, which pulses clock the shift register, thereby determining at once, both the steepness of the generated, ascending or descending sigmoid functions and the overall rate of tonal attack or decay. Thus, in the said system, the overall duration of attack or decay is an inherent inverse function of the steepness of the generated sigmoid function, so that the system cannot vary duration and steepness independently of each other. Generation of the sequences of sigmoid changes in harmonic amplitudes, evident in so many instances of organ pipe attack and decay, require complete tone generating units and large memories for each sigmoid pattern in the envelope of each harmonic of each note.
My recent analyses of the keying envelopes of the harmonics of various kinds of organ pipes have yielded envelopes which not only are complex in form, but which also differ quite substantially and individually for corresponding harmonics of different pipes within each given voice, as well as in different voices which bear different, or even the same, names. Such complex and markedly different envelopes within an organ voice contribute to their voice's signature, or distinctive quality, but as a rule only when they are played in coherent melodies, chords, or counterpoint, somewhat as a familiar human voice often becomes recognizable only when it changes in pitch and quality. By employing large pluralities of tone generating units and large memories for each harmonic of each note, my said co-pending application can duplicate such keying envelopes. However, the volume of required circuitry is economically impractical. The prior art discloses no other, practical means for such duplication.
In my said co-pending application, when a depressed key is released before tonal attack is complete, the initiated attack runs its course before the resulting decay begins. Similarly, when a released key is depressed before the initiated decay is complete, the decay runs its course before the resulting attack begins. Such effects constitute unnatural delays in the organ's responses to interrupted or resumed keyings. The prior art comprehends no means for naturally responsive interruptive or resumptive keying which is also individualized for each separate note.
My said co-pending application discloses means for decoupling pitches within each voice from one another, and for decoupling voices as wholes from each other, to generate an orthogonal two-dimensional sound image duplicating that of organ pipes distributed in a rectangular array, with lower pitches heard as coming from more distant sources, higher pitches heard as coming from nearer sources, and different voices heard as coming from different lateral locations before the listener. The said means comprise pitch decouplers preset by transferred tone-forming information and generating two versions of given tone frequency currents, and voice decouplers preset by switches, receiving the combined output pairs of the said pitch decouplers, and generating four versions of the tone currents. When the four outputs of the voice decouplers are applied to four amplifier-speaker systems constituting a two-dimensional stereophonic system, the said orthogonal sound image is generated.
When, instead, the four outputs of the voice decouplers are applied to four corresponding multiresonant filter sets, when the transfer characteristics of the respective filter sets represent the reenforcement and cancellation effects of sound reflection and refraction in the four corners of a partially open pipe organ chamber, and when the respective outputs of the four filter sets are applied to the four corresponding speaker systems, the resulting two-dimensional sound image is that of organ pipes distributed within such a chamber.
The active, analog filters for such sets are difficult to fabricate because of their collective complexity, lack of standardization of their components, and highly critical values of their comprised resistors and capacitors, with corresponding susceptibility to drift with changes in temperature, humidity, and time. While active, digital filters would be free of such drift, their collective complexity and their need for individualized fabrication detract from their practicability.
The prior art discloses no single circuit comprising stable standardized components and enabling an electronic organ to generate simultaneously, different patterns of individualized decouplings of pluralities of tone currents, in simultaneous duplication of the sounds of different spatial configurations of organ pipes in open or partially enclosed pipe settings.